1. Field of the Invention
The present invention relates to a parallel and selective growth method of carbon nanotubes (CNT), and particularly, to a parallel and selective growth method of carbon nanotubes for electronic-spintronic device applications which grows the carbon nanotubes directly on a wanted position.
2. Description of the Background Art
Recently, a new technique is required because miniaturization and integration of an element are made more rapidly and continually than before. At present, the smallest line width made in the manufactured silicon is about 0.17 xcexcm, and it may be developed to be 0.1 xcexcm of line width. However, it is difficult to develop a silicon having a line width smaller than 0.1 xcexcm using a lithography art at present.
On the other hand, a carbon nanotube (hereinafter, referred to as CNT) found by Ijima of Japan is a new material of next generation which draws attention because its unique electric and mechanic characteristics. In forming a terabit molecule device of nano size, to make the line width less than 0.1 xcexcm without using the conventional lithography art is possible using a self-assembly technique or using selective growth of the CNT having a diameter of 1 nmxcx9c10 nm and moving by one-dimensional proton beam or wiring technique.
If the lithography technique is used, it has advantages for integration because of high ordering and reproducibility, however, it is subordinated to the development of the lithography technique. And the self-assembly technique uses a mechanism in which the materials are formed as nano size, and therefore it is difficult to reproduce and standardize, and it has disadvantages for integrated molecule device application of high yield.
On the basis of results of researches for the CNT, the nanotube may be form a foundation of an electronic engineering. The CNT is chemically inert comparing to another materials which are now studied, and is hard for pierls distortion, and is physically strong and elastic.
FIGS. 1a and 1b are drawings showing examples of conventional CNT growth.
As shown in FIG. 1a, it is difficult to standardize the CNT because a diameter and a length are grown irregularly due to the characteristics in synthesis process, and therefore an individual device is fabricated such that an individual CNT is manipulated and arrayed using a tip of STM (Scanning Tunneling Microscope) or of AFM (Atomic Force Microscope). However, in order to fabricate integrated nano-devices, a countless of CNTs are should be moved on wanted positions and adhered on the positions with an accuracy of atomic scale on a substrate.
Also, as shown in FIG. 1b, the CNT powder is refined a couple of times and dropped on a board on which a pattern is formed using a spin coating or a spit. After that, the CNT on unwanted position is removed using a needle of STM or of AFM, or the CNT decentralized in a solution is picked and arrayed on the board, however it is nearly impossible to fabricate an integrated device in this method.
On the other hand, in most compounding field, a technique which growing vertically for the board are now being developed in order to apply to display. However, even in a CNT film which is grown vertically and well arrayed, lengths of respective CNT are different from each other and intervals between the CNT are unequal, and therefore it is difficult to fabricate an electric device using the CNT in as-grown state.
Therefore, at present, a technique, in which the synthesized nanotubes are collected and refined a couple of times, and after that nanotubes having same diameter and length are separated, is developed in priority. And most researches in application devices fields are searching for reconstructing the grown CNT through the complex refine processes. Therefore, this inefficient fabricating processes are not able to be applied to practical fields such as highly integrated nanoelectronic devices or spintronic devices.
Therefore, an object of the present invention is to provide a parallel and selective growth method of semiconductive and conductive carbon nanotube for developing an electronic device of high integration by growing in horizontal direction on wanted position, between patterns, and on a wanted clearance with in-situ, and to provide an example of the application device.
To achieve the object of the present invention, as embodied and broadly described herein, there is provided a parallel and selective growth method of carbon nanotube for electronic and spintronic device applications comprising the steps of: forming an insulating film on a board; forming a fine pattern of catalyst metallic layer including a contact electrode pad on the insulating film; especially, forming a barrier layer for vertical growth on upper part of the catalyst metallic layer; and directly growing the carbon nanotube between the catalyst patterns.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.